The science of beam weapons

Laser weapons: Fundamentally different from existing weaponry

Essentially every “advanced” weapons technology in history has just been increasing elaboration on one of two ideas: hit an object with another object, and subject an object to an uncontrolled emission of heat energy (blow it up). Occasionally, we have mixed the two approaches together. Directed energy weapons are one of our few real attempts at pioneering a fundamentally different sort of weapon.

We can break this topic down along two basic axes, each with two states. First, there is weapon type, of which there are two: The too-small weapons, the handheld personal phasers of Star Trek, and the too-far weapons, the great, Hoth-like siege engines floating on battleships or orbital platforms. On the other axis, there’s the technology type, which can also be broken down into two major categories: The lasers, focused emitters of various forms of light energy, and the particle beams, super-rapid-fire miniguns that shoot streams of small, mass-carrying particles. There are a few other weapon types we’ll address at the end, but most real world steps toward the lasers of The Future fall neatly into one of the four quadrants in our matrix.

The X Axis – Using laser weapons

Let’s look first at how these weapons might enter the battlefield, regardless of their engineering. There are two basic approaches to implementation: Hand-held beam weapons like we see in Star Trek, and platform based weapons like those we see in reality. Unfortunately, hand-held beam weapons won’t be happening any time soon.

The reasons for this are numerous, but foremost among them is power. Lasers, particle beams, microwave emitters, all of them require great amounts of power, and even if one was willing to haul around a megawatt battery it would eventually need replacing just like regular ammo. We have an informal threshold of 100 kW to reach, past which point, we’ve pretty much decided, our laser will be a killer battle-laser. Before that threshold, presumably, it’s just a really strong pointer.

So-called “blooming” is also a problem, since powerful lasers tend to turn air to plasma as they move through it, creating refracting conditions that defocus the beam. We must stick with platform-mounted lasers since bulky mirror arrays are currently our best way of overcoming the bloom effect. Additionally, the speed and pinpoint accuracy of lasers are almost totally irrelevant on the human-scale battlefield, since distances are short enough for bullets to be functionally instantaneous already, but long enough to make lasers less useful through errors in aiming. There’s really no hint of progress toward the unbroken laser beam we could sweep over a field of enemies for mass bisection and, as you might imagine, a series of micro-second pulses can be really difficult to aim.

Even in the much more foreseeable future of strategic, platform-mounted lasers, weaponizing light requires the use of pulses. The first reason for this, again, is power, but just as important is the mechanism by which laser damage their targets: when a strong enough laser hits a surface, say the wing of a drone, the surface layer will (should) sublimate — that is, go directly from a solid to a gas — and fill the space around the target with a beam-scattering cloud of vaporized metal. You have to wait a while, maybe ten or fifteen microseconds, for that cloud to disburse, or else waste energy while it scatters your beam all over creation. Once the tiny cloud has puffed away, we can send a second pulse, then a third, and so on.

Meh. You should see what they were doing back at the tail end of the Cold War. Google, “Advanced Laser Laboratory” (ALL), “Mobile Test Unit” (MTU), “MIRACL”, “ZenithStar”. Interesting stuff. Instead of shooting down a little RC plane, pardon me- “drone”, they were shooting down Vandal target missiles. Of course the difference was they were using a humongous chemical laser that filled a building (think land based ABL) instead of solidstate lasers. Megawatt class electric lasers (be they LED, fiber, Free-Electron Lasers, or whatnot) is the holy grail.

LASER stands for Light Amplification by Stimulated Emission of Radiation, not Light Amplification and Stimulated Emission of Radiation. You need to stimulate electrons to emit radiation in order to amplify light. It is a cause and effect process.

You are correct that power is a major problem. Bullets are projected by chemical energy, whereas LASERs use electrical energy. An efficient conversion of chemical energy to electrical energy could make portable LASERs more feasible.

mork marvin

so could a chemical conversion from a brain wave to a projectile…..I call them “mind bullets”………..they are nearly as if not more feasible

Tony_Stone

Brains operate using very low energy. The neurons do not have enough energy to electrically message one another, so they use chemical energy to carry the electrical message to the next neuron. A brain would be hard pressed to power a laser or a projectile.

HenryC

I f we do not miniaturize it someone else will, unfortunately but true.

Debaditya Chatterjee

darpa, unfortunately, does not really go by ethics. many weapon systems which are officially bandied about as being in the “proof-of-concept” or “testing” phase are already in limited deployment for classified roles in even more classified locations. what a large number of people fail to realise that there is a decade-long gap between what the us military actually can do, and what the public thinks they can do. they’ve come a long way from the prototype Airborne Anti-missile Laser mounted on a 747. and you’d be surprised to know to what extent your hypotheses about anti-north korean missile defense is accurate.

sferrin

Oh brother. . ..

Debaditya Chatterjee

that’s rather vague……….

sferrin

I thought it summed it up rather nicely.

justsayno

DARPA is unethical and we are sick of our animals being killed to forward the psychopathic tendencies of some sick bastards.

CarlySimon

“…our animals…” ?

Is the GuZoo allowing LASER testing on their guests again?

You can relax jsn, your tinfoil toque remains an effective barrier to even the most powerful LASERs and rational thoughts.

Robert

Man, I thought my cable management skills were sloppy!

Ronald Patrick Marriott

Nikola Tesla invented this not Einstein

Anupam

LASER – It is Light Amplification BY Stimulated Emission of Radiation and not Light Amplification AND Stimulated Emission of Radiation.

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